Increasingly, natural gas vehicles are finding their place on the roads -- especially in municipal and commercial applications. To make natural gas a viable fuel for vehicles, however, it must be compressed. This allows more fuel to be stored per volume, among other things.

So, how is natural gas compressed?

There are many different methods used to compress gasses. When it comes to natural gas, the most common method is the "diaphragm compressor."

The compressor contains a series of chambers, each one equipped with a specially designed membrane. Gas is pumped into the first chamber, where the volume is constricted by the membrane. Once this chamber is full, it is emptied into the next, smaller, chamber and so on down the line until the natural gas has reached the desired pressure.

Once the process is finished, the gas must be kept at pressure in tanks, like those seen in the photograph above.